273 



nema Thuretii. I have only examined a few fully developed cystocarps on slides 

 made by microtome, and they showed that the formation of carpospores is not 

 always limited to the periphery of the conceptacle, but may also take place 

 from the inner part of the great disc-shaped cell at the bottom of the conceptacle, 

 perhaps only because the border of this cell is lobed. 



Referring for the structure and development of the conceptacles of sporangia 

 to Thuret (1. c. p. 94, pi. 49 fig. 4-5) and Solms (1. c. p. 31, Taf. I, fig. 6—7), I shall 

 as to the sporangia only mention that, after the division of the primary sporangial 

 nucleus into four, a fairly long time elapses before the cell-division begins. A great 

 number of sporangia with four nuclei situated about (not exactly) in a vertical 

 series are therefore to be found (fig. 197 B). This was already observed by Thuret, 

 who remarks (1. c. p. 95): "La formation des cloisons est precedee de I'apparition 

 d'espaces clairs qui occupent le centre des futurs spores 

 (fig. 5)". 



As elsewhere (comp. Thuret, 1. c. p. 95, Solms, 1. c. p. 5), 

 the sporangia-bearing specimens seem to be more frequent 

 than the sexual ones also in the Danish waters, but I have 

 not sufficient observations to affirm this with certainty. 



The species is, as elsewhere, rather variable, but cannot 

 be divided into well defined varieties. When growing at 

 low-water mark or in shallow water it is markedly pinnate, 

 almost every joint bearing a pair of branches, and must 

 be referred to f. vulgaris Kiitzing (Tab. phyc. VllI, p. 32, 

 Tab. 66 fig. 2; C. officinalis a, Areschoug 1. c. p. 562; C. offic. 

 f. typica Kjellman, Alg. Arct. Sea p. 86 (114); C. offic. y, 

 Yendo 1902, p. 29, pi. VII, fig. 12, comp. Plate IV figs. 5—6). The specimens growing 

 in deeper water are sometimes not much different from the ones just named, but 

 are usually less branched and have longer joints. In f. vulgaris, the length of these 

 does not reach 2 mm, while in the specimens from deeper water it not rarely 

 reaches 3,5 mm, and even a length of 4,5 mm has been met with. In the extreme 

 forms, the ramification is scarce and irregular, not pinnate, and the branches are 

 often given off at various sides, though a tendency to branching in one plane is 

 to a certain degree pronounced. Such forms may be named f. profunda Farlow 

 "(Mar. Alg. New. Engl., 1881, p. 179). In the Kattegat and the Sams0 waters they are 

 frequently coarser than the typical form, the joints being cylindrical, about 1 mm 

 thick, and agree then fully with the description of f. robusta Kjellm. (1. c. p. 86 (114)). 

 This form has been collected in several places in the named waters in depths from 

 10 to 19 meters (Plate IV fig. 8). 



The species is commonly spread in all the Danish waters with proportionally 

 high salinity, including the Samso waters, where it is very common. It grows usually 

 on stones, but may also be fixed to shells of molluscs (Purpura, Littorina, Buccinum, 

 bivalves), on wood, and more rarely on Algse (Furcellaria). It often forms associations 



U. K. U. Vidensk. Selsk Skr.. 7. Hitkke, nutui videiisk. ug malhcm. Aid. VII. 2. 35 



Fig. 197. 

 Corallina officinalis. A, with 

 undivided nucleus; B, with four 

 nuclei but yet undivided ; C, with 

 completed divisions. 230:1. 



